The success of the internet has led to IP technology migration in telecommunication networks. The emergence in mobile and fixed telecommunication networks of a variety of IP-enabled services and technologies, such as voice over IP (Nb/IP and Iu/IP) and SIGTRAN, now requires the customer to construct an IP backbone transport infrastructure.
Telecommunication networks interoperate with an IP backbone by means of associated local access or core networks accessing the IP backbone and exchanging telecommunication sessions over the IP backbone. PSTN (dial-in access), Global System for Mobile Communications (GSM), and Universal Mobile Telecommunications System (UMTS) network are examples of telecommunication network which can access and exchange telecommunication sessions over an IP backbone transport network.
An IP backbone transport network can have different structures. A network structure that is adopted in IP backbone networks for telecommunications is a duplicated or dual ring structure. This type of IP network structure is adopted because routers and switches are not considered as carrier class nodes but the availability still has to be as good as in Time Division Multiplexing (TDM) networks.
FIG. 1 depicts an example of a simplified dual ring IP backbone network accessible by telecommunication network nodes. In FIG. 1, a first ring 1 of the dual ring network is represented by solid line interconnecting site routers (R1) 5 of hubs 4 and the second ring 2 is represented by dotted line interconnecting the other site routers (R2) 6 of hubs 4. Any type of traffic engineering can be used inside the IP backbone network. For example, Multi Protocol Label Switching (MPLS) can be used to allow traffic engineering. Telecommunication nodes 7 can access and transport sessions to one another over the IP network.
Routers 5, 6 of IP network are Provider Edge routers. The traffic engineering allows the path and the interfaces by which traffic shall flow to be predefined. Insofar as Label Switched Path (LSP) setup of the IP backbone, from each Provider Edge (PE) router 5, 6 in the network there is a straight LSP, a local LSP and a crossed LSP defined. This means that in non-failure scenarios, Nb/IP traffic injected to a router (R1) 5 in the first ring 1 is confined always in the first ring 1 until it reaches the final telecommunication core or access nodes. The local LSP is only used for site local traffic. This configuration provides the best resilience and fastest convergence
Load balancing in the telecommunication system is carried out in the telecommunication nodes 7. For example in UMTS applications, nodes 7 can be for example media gateway (MGW) nodes of the core network. Load balancing can be carried out in each media gateway (MGW) node when it is selected by the Mobile Switching Centre (MSC-S) (not shown), by equally selecting an IP interface per new call in round robin manner forwarding once to the first ring 1 and the next time to the second ring 2. One half of the IP interface of node 7 forwards all its traffic to site router 5, the other half of the IP interface forwards to site router 6. Following the straight LSP then the Nb user plane stays in one ring. Note that the upstream and the downstream of the same Nb connection can be using different rings because each MGW decides independently which IP interface is used for a connection.
There is a need for systems and methods that can provide more efficient load balancing of telecommunication sessions over a dual ring topology internet network.